How do magnesium and oxygen combine to form magnesium oxide?

Magnesium and oxygen combine to form magnesium oxide (MgO) through an oxidation-reduction (redox) reaction.

When magnesium burns in oxygen, it acts as a reducing agent, while oxygen acts as an oxidizing agent. The process involves the transfer of electrons: each magnesium atom gives up two electrons to become a positively charged magnesium ion ($M{g}^{2+}$), and each oxygen atom accepts those two electrons to become a negatively charged oxide ion ($O^{2-}$).1

The resulting product is an ionic compound held together by the electrostatic attraction between these oppositely charged ions. This reaction is highly energetic; for instance, when magnesium is heated above 645 °C (1,190 °F) in dry air, it burns with a characteristic bright white light and intense heat. Additionally, magnesium oxide can be produced by roasting magnesium carbonate or magnesium hydroxide.1234